Molding finely powdered lignocellulosic fibers into high density materials

ABSTRACT

A molded fiber product is made from plant fibers containing lignin. Plant fibers ranging in size below 0.5 mm are used. Binding agents and other additives may be mixed with the fibers to enhance product or process performance. The plant fiber mixture of fibers and additives are heated at temperatures between 40 degrees C. and 300 degrees C. The heated fibers are compressed in a mold to an average density of at least 960 kg/m3. Compression pressures of at least 3.4 MPa are used. The compressed fiber product is released from the mold and the mold may be reused. A thermoset molded plant fiber product is provided having characteristics and qualities similar to engineering grade thermoplastics and thermoset plastics.

This application is a 35 U.S.C. §371 application of International PCTApplication No. PCT/CA98/00011; filed Jan. 7, 1998.

BACKGROUND OF THE INVENTION

This invention relates to the manufacture of molded materials fromfinely powdered plant materials containing lignin. In particular, theinvention provides a method of making a high density molded thermosetpowdered plant material with characteristics and qualities similar toengineering grade thermoplastics and thermoset materials. Plant fibersof less than 500 microns in size are compressed into resilient, moldedmaterials. Products manufactured by using the method of the inventionare also described.

RELATED ART

In the systems of the prior art, long strands, fibers, flakes or chipsof wood are commonly used to manufacture low and medium density boards,felts or other materials for building and other uses. However, thisconventional technology has focussed on physically bonding such piecesinto agglomerations forming the boards, felts and other materials. Thestrength characteristics of the final products were ultimately limitedby the strength of the individual fibers that had been bonded or gluedtogether and the interfacial bonds between the fibers and the glue.Typically, wood fibers, chips, and flakes much larger than 3000 micronswere used as a raw material source for these conventional manufacturingtechniques.

Furthermore, prior art systems typically employed multiple stages toform the desired products. For example, intermediate felts and othershapes would be formed and would then be subjected to additionalchemical or physical treatments including calendaring, pressing,dewatering or other processes.

In general, wood treatment related technologies have developedseparately from efforts to utilize other naturally occurring plantmaterials. Whether in the field of wood processing technology or in theprocessing of other plant materials, those efforts have taught andadvanced the use of larger raw material particles of sizes averagingwell above 3000 microns.

One attempt at physically bonding somewhat smaller particles of straw isbriefly described in UK patent application number GB 2 265 150 A, datedSep. 22, 1993 by Brian Harmer (hereafter called “Harmer”). However, thatreference teaches the use of straw fibers within a broad range of fibersizes, all of which are much larger than the plant fibers of the presentinvention. Indeed, Harmer, teaches the use of a different process usingmuch larger straw fibers of various sizes within a broad range of morethan 500 microns and up to about 3000 microns. Harmer teaches that strawparticles within a range of 500 microns to 2000 microns are preferred.Harmer, like many references in the area of wood fiber technology,teaches away from the use of very fine powders of less than 500 micronsin diameter. Further, Harmer teaches the use of styrene to form aprotective outer skin on the resulting product to inhibit waterabsorption.

In addition, the use of a broad range of particle sizes of up to 3000microns in that process will result in a final product with a highlytextured surface having discreet particles which are clearly visible tothe naked eye. In part, the use of larger straw particles was taught byHarmer as a means of avoiding difficulties associated with that process,including the use of a two stage phenolic resin and hexamine as a crosslinking agent. The phenolic glue system, once polymerized, produces aphysical bond between the fibers and the glue. To reinforce thisphysical bond, Harmer uses hexamine as a crosslinking agent to enhancethe physical bonding characteristics. Also, Harmer does not teach how toavoid problems associated with the application of conventional mixingtechniques to satisfactorily combine a powdered two stage phenolic resinincluding hexamine with very finely powdered straw fibers of sizes below500 microns. Harmer also does not teach how to avoid premature reactionsof liquid additives or other powdered additives which may be included ina plant fiber formulation.

DESCRIPTION OF THE PRESENT INVENTION

In the present invention, very finely powdered lignocellulosic plantfibers of below 500 microns are used. Typically, such fibers will have amaximum length of 500 microns, with particle diameters ranging betweenabout 20 to 50 microns. It is understood that such particles areirregularly shaped, within a broad range of sizes of up to 500 micronsin effective size. In many applications, plant fibers of less than 250microns will be preferred. It will be understood by those skilled in theart that the size of such particles will typically fall within a rangeof particle sizes characterized by screening or other suitable gradingtechniques. In some instances, the size of such particles is referred toas an effective diameter, or effective size however, the actual size ofa given irregularly shaped particle will not necessarily correspond tothe effective size of the particle. Rather, the effective size willrelate to the tendency of the particle to pass through a sieve or otherscreening or grading device.

Plant fiber particles containing lignin are desired to enhance thebinding characteristics of the thermoset binding agents describedfurther below.

Finely powdered wood fibers derived from hardwoods and softwoods may beused provided they have not been pretreated to remove significantamounts of lignin and related naturally occurring components of wood.Other suitable lignocellulosic materials include finely powdered flax,hemp, grasses, jute, and various agricultural products and waste plantmaterials containing lignin.

The finely powdered plant fibers are preferred to have a moisturecontent of less than about 50 per cent by weight and more preferably,between about 5 per cent to about 20 per cent by weight. For example, inprocesses utilizing polymeric diphenyl methane di-isocyanate,substantial concentrations of moisture in the plant fibers will enhancebonding within the plant fiber mixture.

According to the method of the present invention, the finely powderedplant fibers are mixed with a thermoset binding agent, and preferably, arelease agent. The plant fiber and additive mixture is introduced to aheated mold operating between 40 degrees C. and 300 degrees C. Incertain systems, lower reaction temperatures of about 40 degrees C. willbe effective at relatively higher pressures. For example, binding agentssuch as polyester resin in plant fiber may be mixed with organicperoxide in plant fiber at about 40 degrees C. In heat sensitive bindingagent systems, operating temperatures of up to 300 degrees C. may beapplied for relatively short pressing cycles. In such cases, some degreeof surface charring or other imperfections may arise. Such imperfectionsmay be removed by subsequent operations, or may remain if they will notdetrimentally affect the product's expected performance. Preferredoperating temperatures range between 100 degrees C. and 220 degrees C.,and more preferably between 160 degrees C. and 220 degrees C.

The contents of the mold are heated and compressed under pressures of atleast 500 psi, with preferred operating pressures greater than 1000 psiand higher.

The resulting products have average densities of at least 60 pounds percubic foot. Higher average product densities of more than 80 pounds percubic foot and more than 90 pounds per cubic foot are also provided.Higher product densities will in many instances provide for enhancedphysical and mechanical characteristics. Such characteristics willcorrespond to specific formulations and may include one or more of suchproperties as increased strength, impact and wear resistance, decreasedwater absorption, and increased dimensional stability.

In one embodiment of this invention, a high density plant material ismanufactured by a method comprising the steps of:

(a) introducing into a mold a mixture comprising powdered plant fiberparticles of less than 500 microns, thermoset binding agent between atleast 0.1 per cent and 50 per cent by weight of the plant fiberparticles;

(b) operating the mold at a temperature between 40 degrees C. to 300degrees C.;

(c) applying a pressure of at least 500 psi to the contents of the mold;

(d) compressing the contents of the mold to an average density of atleast 60 pounds per cubic foot; and

(e) releasing the contents from the mold.

Internal or external mold release agents may be used in thoseapplications requiring a release additive. An external mold releaseagent may be introduced to the mold separately from the plant fibermixture. Alternatively, mold release additives may be added to the plantfiber mixture to be compressed within the mold. Although a mold releasemay be desirable in many instances, such additives may not be requiredin all applications.

In another embodiment of this invention, a high density plant fiberproduct is formed by using a method comprising the steps of:

(a) mixing one or both of (i) a first amount of powdered plant fiber ofless than 500 microns and a thermoset resin and (ii) a second amount ofpowdered plant fiber of less than 500 microns and one or more additives;

(b) preparing a plant fiber mixture containing thermoset resin in aconcentration of between 0.1 per cent and 50 percent by weight ofpowdered plant fiber comprising mixing one or both of the first andsecond amounts with other additives;

(c) introducing the mixture of plant fibers and additives into thecavity of a mold;

(d) compressing the mixture by applying a pressure of at least 500 psito the surface of the mixture;

(e) heating the mold cavity to between 40 degrees C. to 300 degrees C.;

(f) compressing the contents of the mold to a density of at least 60pounds per cubic foot; and

(g) removing the compressed contents from the mold.

A combination of one or more of mineral and non-mineral additives may beprovided to enhance the process or the performance characteristics ofthe final products. By way of example, such additives may include one ormore synthetic additives including, synthetic catalysts and syntheticpigments, glass microspheres, glass fibers, carbon fibers, aramidfibers, metallic particles and other compatible additives. The use ofthese additives may provide enhanced product strength, impactresistance, wear resistance, dimensional stability and other favourableproduct qualities. Concentrations of additives in plant fiber mixturesof up to 50 per cent by weight of fiber are provided. In one aspect ofthis invention, mineral additives, including silicate additives, silicaor silica sand, in concentrations up to 50 percent by weight of plantfiber, are provided. Coupling agents may be added to improve the bondingof the inert mineral and non-mineral additives within the final product.

In another aspect of this invention, a plant fiber product is formed bymolding a desired shape to an average density of at least 60 pounds percubic foot. The product is made substantially from powdered plant fiberscontaining protolignin, a thermoset binding agent in a concentration ofbetween about 0.1 per cent and 50 per cent by weight of plant fiber, anda release agent. The fibers have an effective size of less than 500microns.

In another aspect, the invention includes a plant fiber product mixturecomprising protolignin containing plant fibers of between 20 and 500microns in size, a release agent, and a concentration of binding agentof less than 50 per cent by weight of plant fibers.

FIG. 1 is a graphic representation of the typical stress-strainrelationship in a product of the present invention made from finelypowdered natural fibers mixed with a binding agent and compressed inaccordance with the method.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with the present invention, thermoset binding agents areused to react with and bind together finely powdered lignocellulosicplant fibers. The binding agents include unsaturated polyester resin,polymeric diphenyl methane di-isocyante, methane di-isocyante, melamine,urea, phenolic formaldehydes, and ester containing compounds.

Traditionally, phenolic formaldehyde resins have presented environmentaland health concerns in certain applications. Accordingly, polyester andPMDI resin systems are preferred in those applications where such issuesmay arise.

Thermoset binding agents are desirable to provide products that arestable under a broad range of heating and temperature conditions. Theparticular binding agent may be selected to achieve the most desirableprocess conditions and product characteristics for certain applications.For example, polymeric diphenyl methane di-isocynate (PMDI) is desirablein many applications using plant fibers having some residual watercontent. The presence of moisture within the range of about 5 to 50 percent by weight of plant fiber is acceptable, with a preferred moisturecontent between about 5 per cent and 20 per cent by weight of fiber.

The presence of moisture in the fibers permits or causes the crosslinking and other reaction mechanisms which occur during the compressionof the fiber mixtures under elevated temperatures and pressures of themethod of this invention. It is noted that the specific reactionmechanism which may be involved is not claimed or considered to be anessential element of the present invention.

In one preferred aspect of the invention a thermoset resin, inparticular, polymeric diphenyl methane di-isocynate (PMDI) is added tofinely powdered plant fibers of less than 250 microns. PMDIconcentrations ranging between 0.1 per cent and 50 per cent by weight ofplant fiber can be used. PMDI concentrations of between 1 per cent and25 per cent by weight are preferred in certain instances where othersuitable additives are also included in the plant fiber mixture to becompressed. Other useful mixture formulations using relatively smallconcentrations of binding agents such as PMDI are also within the scopeof this invention.

If one or more reactive additives will be included in the plant fibermix to be molded into a product, sequential dilution or mixing of theingredients may be used to inhibit premature reaction of the mixtureingredients. Similarly, if small concentrations of additives will beutilized, and it would be difficult to accurately disperse thoseadditives in one mixing step, two or more sequential mixing steps ordilution steps may be used to more accurately and precisely regulate thefinal mixture concentrations.

In one example, an additive such as a catalyst or release agent is to beadded in concentrations of about 1 per cent to a relatively small batchof plant fiber mixture. A predetermined amount of the additive may beadded to a first batch of powdered plant particles, also provided in apredetermined amount. The initial mixing ratios may be calculatedaccording to the technical specifications or limitations of the weightmeasuring and mixing equipment to be used in the process.

If the available equipment is satisfactory for measuring and mixing abatch of 10 per cent weight by weight concentration of additive in woodfiber, 10 parts by weight of additive may be mixed with 100 parts ofwood fiber to give a first batch of plant fiber mixture A. Thereafter,if the target concentration of additive is 1 per cent by weight of woodfiber in the final plant fiber mixture B which is to be compressed, aportion of the first batch A may be measured, diluted and mixed a secondtime based on a final mixture of 10 parts by weight of the first batch Aand 100 parts by weight of powdered wood fibers. It will be appreciatedthat this example is based on three steps of measuring, diluting, andmixing additives to the plant fibers based on mixture ratios of 1 to 10in both instances. However, it will be understood that a differentnumber of sequential dilution steps may be used where it is necessary ordesirable to do so, and that different dilution ratios may be used toachieve the target concentrations of thermoset resin, additives,including release agent, in the intermediate and final plant fibermixtures. By way of further example, in some instances, it may desirableto sequentially mix only one ingredient with the plant fiber materialand then mix an amount of that intermediate mixture with the remainingingredients, and if necessary, additional plant fibers, to yield thedesired concentrations of thermoset resin, additives and release agent.The resulting mixture may then be compressed within the mold.

It will also be understood that although this example referred to mixingbatches of plant fiber mixtures, this process may also be adapted tocontinuous mixing operations.

In many instances it will be very desirable, but not necessary, toinclude release agents within the plant fiber mixture to be compressed.Release agents will enhance the ability to successfully remove thepressed product part from the mold after completion of the compressionstep. For example, relatively small concentrations of stearates havebeen found to be useful release agents in applications includingthermoset binders including PMDI.

Metallic stearate may be included in formulations including PMDI andplant fiber mixtures to enhance the release mechanism of the mixturewithin the mold. For example, zinc stearate, calcium stearate andmagnesium stearate concentrations of between about 0.01 per cent andabout 5 per cent by weight of plant fiber were useful. Metallic stearateadditives provide for improved product characteristics includingmoisture resistance and material flow.

Other examples of acceptable release agents to be used in PMDI and plantfiber mixtures include potassium oleate, or silicone based or wax basedrelease agents. Again, the selection of the desirable agent will dependupon a number of process parameters and product qualities desired to beachieved in particular applications.

In another aspect of this invention, substantial quantities of mineraland non-mineral additives may be added to the plant fiber formulationsto impart beneficial physical and mechanical characteristics. Forexample, the introduction of silicates, silica, silica sand, or otheradditives into the plant fiber formulations can also inhibit surfaceabrasion and wear of the finished products. Concentrations of silicates,silica or silica sand of less than 50 per cent by weight of plant fibermay be used to provide improved product performance in comparison tovarious conventional materials. Concentrations of silicates of more than2 per cent by weight of plant fiber are preferred.

When using silicate, silica or sand based plant fiber formulations itmay be desirable to include a coupling agent. For example, silane is auseful coupling agent in plant fiber mixtures including sand, PMDI andlignocellulosic plant fibers.

In other aspects of this invention, it is possible to include syntheticand plant fiber materials having specific physical characteristics toimpart other desirable product qualities. For example, synthetic fibers,carbon fibers, glass fibers and natural fibers may be added to the plantfiber mixture to be pressed. It is possible to use core materials suchas compressed lignocellulosic plant fiber mixtures of the presentinvention as a base supporting added outer layers of carbon fiberlaminates and glass fiber laminates. Such laminates may be selected toprovide improved dimensional stability or other qualities characterizedby the final laminate product.

In general, operating temperatures for the molding step range between 40degrees C. and 300 degrees C. Temperature ranges between 100 degrees C.and 220 degrees C. are preferred. The mold will typically be operatedwithin a relatively narrow temperature band to permit better controlover process parameters and product consistency. Compression pressuresmay be selected from at least 500 psi to a much higher range ofcompression pressures of 1000 psi, 2000 psi and more. The selection ofspecific temperature and pressure process variables will affect thein-mold pressing time and other parameters in the molding process.Certain additives, including mineral and non-mineral additives, forexample, silica or silica sand, may be added to reduce pressing cycletimes by improving heat conductance of the plant fiber mixture. It willbe understood that complex product formulations or geometries maysignificantly alter the actual in-mold residence time for a particularprocess application.

Other additives may be included in the plant fiber formulation,depending upon the final product characteristics which are sought.Additives including fire retardants, colouring agents, surface agents toimpart anti slip features or esthetic characteristics may also be usedin certain plant fiber formulations. Minute quantities of fine metallicparticles or small multicoloured glass particles may be added at betweenabout 0.1 per cent and about 10 per cent by weight of fiber to achievedesirable surface finishes and appearance.

The use of finely powdered plant fibers also enhances the appearance ofthe outer surface of the final product. If colouring agents are usedwith fibers below 500 microns, it is possible to achieve far superiorblending of colours and consistency in the outer appearance without anynoticeable fiber-like texture in the final product. Further, the use offinely powdered plant fibers enhances the uniformity of the appearanceand texture throughout the product. It is possible to produce a productthat has consistent colour and other textural characteristics that gobeyond the outer surfaces. This characteristic is unique in that manyother systems merely develop a product with a thin outer skin that wouldbe unsuitable for sanding or other repair work when damaged, and incases where colour differences arise, additional paint or other repairsmay be required.

The products of the present method exhibit exceptional performancecharacteristics including relatively little water absorption, increasedtensile strength and impact resistance. The specifications of the finalproduct may be designed to achieve particular features by, for example,adjusting the final average density of the product part. The presentmethod may be used to impart densities which are significantly higherthan the densities of the corresponding raw plant fiber material.Indeed, many of the product formulations subjected to higher temperatureand pressure treatments of this method result in products havingspecific gravities well in excess of 1.0 as compared with many of theprior art systems based on wood particles which resulted insignificantly lower densities.

The products of this process may be specifically designed to developintegral low density and high density zones. Unlike many conventionalmaterials, including plastics and metals, which necessarily exhibit asubstantially uniform density after molding a part, the products of thisinvention may be designed to have distinct density zones, with eachhaving its own desirable physical characteristics. Accordingly, certainzones may be selected to experience a relatively higher degree ofcompression to achieve higher localized densities in comparison to otherlower density zones which have been compressed to a lesser degree. Forexample, the high density zones may be desirable for added strength,durability characteristics and the lower density zones may be providedin localized areas to permit easier trimming, cutting, or fasteningsteps including drilling, or nailing or other working of the productmaterial.

Table 1 shown below illustrates typical properties of productsmanufactured according to the present invention based on formulations ofplant fibers and thermoplastic binding agents identified as formulationsA to D inclusive.

TABLE 1 Mechanical and physical properties of examples of natural fibercompositions of the invention. Tensile Tensile Hardness Water ThicknessComposition/ Modulus Strength Failure Rockwell Absorption Swell Property(GPa) (MPa) Strain (%) M (%) (%) ASTM No. D638 D638 D638 D785 D1037D1037 Composition A 4.3 37.3 1.4 31.16 4.9 4.0 Composition B 4.4 40.41.4 63.12 3.8 3.8 Composition C 4.9 45.5 1.5 64.20 2.7 3.0 Composition D5.8 45.4 1.6 79.42 6.3 7.0

Table 2 illustrates typical properties of formulations E and F,described further below.

TABLE 2 Properties of Glass Fibers and Carbon Fiber CompositionsComposition/ Tensile Modulus Tensile Strength Property (GPa) (MPa)Failure Strain % ASTM No. D638 D638 D638 Composition E 5.3 42.9 1.2Composition F 5.4 36.8 0.9

Table 3 and 4 below show the ingredients and process conditions used toproduce multiple test samples of each formulation. Concentrations ofresin (PMDI) and other additives are given as per cent (w/w) of plantfiber. Test data such as process temperature, pressure and cooking timeare average values calculated for the tested samples for the variouscompositions.

TABLE 3 Ingredients in Compositions A to F (% w/w of wood fibers lessthan 250 microns) Resin Zn Ca Silica Na- lass Carbon Composition (PMDI)Stearate Stearate Silane Sand silicate ibers Fibers A 5 0.25 0.025 0.5 00 0 0 B 10 0.5 0.05 0 0 0 0 0 C 10 0.4 0.02 0.4 10 0 0 0 D 10 0.5 0.050.5 0 25 0 0 E 10 0.4 0.02 0.2 0 0 5 0 F 10 0.4 0.02 0.2 0 0 0 5

TABLE 4 Process Conditions and Resulting Sample Thickness Pressure Temp.Cure time Composition (psi) (Degrees C.) Thickness/mm (sec) A 2800 1356.87 100 B 2900 130 6.6 140 C 2900 122 6.11 122 D 2850 135 6.05 135 E2800 122 6.27 255 F 2800 120 6.2 255

TABLE 5 A Comparison of Physical and Mechanical Properties of a SampleProduct of the Invention (Composition B) With Other Materials. MaximumTensile Tensile Failure Op. Density Strength Modulus Strain TemperatureMaterial/Units (g/cc) (Mpa) (Gpa) (%) (° C.) Composition B 1.34 40.4 4.41.4 200 P (propylene) 0.91 36.0 1.31 22 100 Wood- 1.10 20.7 1.75 18.5100 Thermoplastic Flax- Thermoplastic P (propylene) 0.96 36.3 2.20 >18100 Grade 4/PP 0.98 29.4 2.0 >18 100 P (ethylene) Grade 4/PE Nylon-Glass33% 1.38 115 5 4 100 DMC P(ester) 1.80 40 9 3 130 PEEK-Carbon 1.40 24014 1.6 255 30%

TABLE 6 Characteristics of Natural Fibers and Synthetic Fibers. TensileTensile Density Modulus Strength Failure Strain (g/cc) (GPa) (MPa) (%)Natural fibers: Flax 1.52 100 0.84 2.0 Hemp 1.52 70 0.92 1.7 Kenaf 1.5253 0.93 1.6 Sisal 1.52 38 0.86 2.7 Wood ˜1 10-80 ˜1.5 1-3 Jute 1.52 600.86 2.0 Synthetic fibers: Glass 2.5 72 2.5 2.5 Carbon 1.9 380 2.0 1-2Aramid 1.4 125 2.8 2-4 Metals Aluminum 2.8 73 0.47 10   Steel 7.8 2000.40 30  

FIG. 1 illustrates typical stress-strain behavior of a formulation madewith natural fiber material. This example is illustrative of the typicalstress-strain behavior exhibited by many product formulationsmanufactured in accordance with this invention. However, it will beunderstood that the specific data or values will vary according to theparticular formulations and process parameters used in each case.

Further advantages of the present invention also include products withbeneficial esthetic qualities including the smell of the final products.For example, finely powdered flax particles may be compressed underprocess conditions to yield a final product that is free fromundesirable smells otherwise associated with processed flax.Consequently, powdered flax may be included in formulations describedherein to produce parts for use in a wide variety of industries,including the automotive, aviation and electronics industries withoutimparting such undesirable smells.

Further useful modifications of the methods and products disclosedherein may be made without departing from the scope of this invention.Such useful modifications will be apparent to those skilled in the artand are intended to fall within the scope of the following claims.

REFERENCES

1. John Balantinecz and Tony Redpath on “Progress in Woodfiber-plasticcomposites.

Applications: from Autoparts to Composite Lumber”, Ontario Apr. 24,1994. Sponsored by University of Toronto, Ontario Center for MaterialsResearch, UIR—University of Wisconson & USDA—Forest Service, ForestProducts Laboratory.

2. A. S. Hermann and H. Hanselka, Institute of Structural Mechanics,German Aerospace Research Establishment on “Composites with biologicalfiber and matrix components”.

3. Durafiber specification sheet, Cargill Limited.

4. R. J. Crawford, Plastic Engineering, 2e, Pergamon Press, U.K.

I claim:
 1. A method of manufacturing a high density plant fibermaterial from powdered plant fibers comprising the steps of: introducinginto a mold a mixture comprising powdered plant fiber particles having asize of less than 500 microns (5×10⁻⁴ m) wherein the powdered plantfiber particles consist essentially of natural plant fibers which havenot been preformed, thermoset binding agent between at least 0.1 percent and 50 per cent by weight of the plant fiber particles, and thethermoset binding agent is selected from the group of agents consistingof unsaturated polyester resin, polymeric diphenyl methane di-isocyante,methane di-isocyante, melamine, urea, phenolic formaldehydes and estercontaining compounds; operating the mold at a temperature between 40° C.to 300° C.; applying a pressure of at least 500 psi (3.4 Mpa) to thecontents of the mold; compressing the contents of the mold to an averagedensity of at least 60 pounds per cubic foot (960 Kg/m³); and removingthe contents from the mold.
 2. The method of claim 1 wherein theconcentration of thermoset binding agent is more than 1 per cent andless than 25 per cent by weight of plant fibers.
 3. The method of claim1 wherein the concentration of thermoset binding agent is less than 10per cent by weight of plant fibers.
 4. The method of claim 1 wherein theconcentration of thermoset binding agent is between 10 per cent and 25per cent by weight of plant fibers.
 5. The method of claim 2 wherein thesize of the plant fiber particles is less than 250 micron (2.5×10⁻⁴ m).6. The method of claim 3 wherein the size of the plant fibers is between50 (5×10⁻⁵ m) and 250 microns (2.5×10⁻⁴ m).
 7. The method of claim 2wherein the pressure is more than 1000 psi (6.8 Mpa).
 8. The method ofclaim 3 wherein the pressure is more than 2000 psi (13.6 Mpa).
 9. Themethod of claim 5 wherein the pressure is more than 3000 psi (20.4 Mpa).10. The method of claim 7 wherein the contents of the mold arecompressed to an average density of more than about 75 pounds per cubicfoot (1200 Kg/m³).
 11. The method of claim 7 wherein the contents of themold are compressed to an average density of more than 80 pounds percubic foot (1280 Kg/m³).
 12. The method of claim 8 wherein the contentsof the mold are compressed to an average density of more than 90 poundsper cubic foot (1440 Kg/m³).
 13. The method of claim 1 wherein themixture further comprises one or more mineral additives and non-mineraladditives, the combination of mineral additives and non-mineraladditives being in a concentration of between 2 per cent to 50 per centby weight of plant fibers.
 14. The method of claim 1 wherein the mixturefurther comprises mineral additives in a concentration of up to 30 percent by weight of plant fibers.
 15. The method of claim 1 wherein themixture further comprises mineral additives in a concentration of up to25 per cent by weight of plant fibers.
 16. The method of claim 1 whereinthe mixture further comprises mineral additives in a concentration of upto 10 per cent by weight of plant fibers.
 17. The method of claim 13wherein the mixture further comprises a coupling agent.
 18. The methodof claim 17 wherein the concentration of coupling agent is less than 0.5per cent by weight of the mineral additives.
 19. The method of claim 17wherein the coupling agent is silane.
 20. The method of claim 17 whereinthe mineral additives are one or more mineral additives selected fromthe group of mineral additives consisting of silicates, silica, silicasand, and glass particles.
 21. A method of forming a high density plantfiber product from powdered plant fibers, comprising the steps of: astep of mixing one or both of (i) a first amount of powdered plant fiberhaving a size of less than 500 microns (5×10⁻⁴ m) wherein the powderedplant fibers consist essentially of natural plant fibers which have notbeen preformed, and a thermoset binding agent wherein the thermosetbinding agent is selected from the group of agents consisting ofunsaturated polyester resin, polymeric diphenyl methane di-isocyante,methane di-isocyante, melamine, urea, phenolic formaldehydes and estercontaining compounds and (ii) a second amount of powdered plant fibershaving a size of less than 500 microns (5×10⁻⁴ m) and one or moreadditives; preparing a plant fiber mixture containing thermoset bindingagent, wherein the thermoset binding agent is selected from the group ofagents consisting of unsaturated polyester resin, polymeric diphenylmethane di-isocyante, methane di-isocyante, melamine, urea, phenolicformaldehydes and ester containing compounds, in a concentration ofbetween 0.1 per cent and 50 percent by weight of powdered plant fiber,comprising mixing one or both of the first and second amounts with otheradditives; introducing the mixture of plant fibers, additives, and otheradditives into the cavity of a mold; compressing the mixture by applyinga pressure of at least 500 psi (3.4 Mpa) to the surface of the mixture;heating the mold cavity to between 40° C. to 300° C.; compressing thecontents of the mold to a density of at least 60 pounds per cubic foot(960 Kg/m³); and removing the compressed contents from the mold.
 22. Themethod of claim 21 wherein the plant fibers have a size of less than 250microns (2.5×10⁻⁴ m).
 23. The method of claim 22 wherein the pressure ismore than 1000 psi (6.8 Mpa) and the contents of the mold are compressedto an average density of more than 80 pounds per cubic-foot (1280Kg/m³).
 24. The method of claim 21 wherein the contents of the mold arecompressed to an average density of more than about 75 pounds per cubicfoot (1200 Kg/m³).
 25. The method of claim 24 wherein the concentrationof thermoset binding agent is between 10 per cent and 25 per cent byweight of powdered plant fiber.
 26. The method of claim 24 wherein themixture of plant fibers and additives comprises a metallic stearaterelease agent.
 27. The method of claim 25 wherein the mixture of plantfibers and additives comprises a release agent mixture of zinc stearateand calcium stearate.
 28. The method of claim 26 wherein the releaseagent comprises magnesium stearate.
 29. The method of claim 22comprising the step of mixing a release agent with a predeterminedamount of powdered plant fibers having a size of less than 250 microns(2.5×10⁻⁴ m).
 30. A plant fiber product compressed to an average densityof at least 60 pounds per cubic foot (960 Kg/m³) made substantially frompowdered plant fibers consisting essentially of natural plant fillerswhich have not been preformed, the fibers having a size of less 500microns (5×10⁻⁴ m), and a thermoset binding agent in a concentration ofbetween about 0.1 per cent and 50 per cent by weight of plant fiber,wherein the thermoset binding agent is selected from the group of agentsconsisting of unsaturated polyester resin, polymeric diphenyl methanedi-isocyante, methane di-isocyante, melaminie, urea, phenolicformaldehydes and ester continuing compounds.
 31. The product of claim30 wherein the average density is at least 80 pounds per cubic foot(1280 Kg/m³).
 32. The product of claim 30 having an average density ofat least 90 pounds per cubic foot (1440 Kg/m³).
 33. The product of claim31 wherein the size of the plant fibers is less than 250 microns(2.5×10⁻⁴ m).
 34. The product of claim 30 wherein the concentration ofthermoset binding agent is less than 25 per cent by weight of plantfibers.
 35. The product of claim 30 wherein the concentration ofthermoset binding agent is between 10 per cent and 25 per cent by weightof plant fibers.
 36. The product of claim 30 comprising mineraladditives in a concentration of less than 50 per cent by weight of plantfibers.
 37. The product of claim 30 comprising mineral additives in aconcentration of less than 25 per cent by weight of plant fibers. 38.The product of claim 30 comprising mineral additives in a concentrationof less than 10 per cent by weight of plant fibers.
 39. The product ofclaim 37 comprising a coupling agent.
 40. A plant fiber product mixturecomprising plant fibers consisting essentially of natural plant fiberswhich have not been preformed and are between 20 (2×10⁻⁵ m) and 500microns (5×10⁻⁴ m) in size, a release agent, and a concentration ofthermoset binding agent of less than 50 per cent by weight of plantfibers, wherein the thermoset binding agent is selected from the groupof agents consisting of unsaturated polyester resin, polymeric diphenylmethane di-isocyante, methane di-isocyante, melamine, urea, phenolicformaldehydes and ester containing compounds.
 41. The product of claim30 comprising one or more additives selected from the group of additivesconsisting of a release agent; catalyst; metallic particles; fireretardant; a surface agent; pigment; colouring agent; a mineral additiveselected from the second group of additives consisting of silicates,silica, silica sand, sand, glass fibers, and glass beads; and a couplingagent.
 42. The product mixture of claim 40 comprising mineral additivesin a concentration between 1 per cent and 50 per cent by weight of plantfibers and a coupling agent.
 43. The product mixture of claim 42 whereinthe concentration of mineral additives is more than 2 per cent by weightof plant fibers.
 44. The product mixture of claim 43 wherein thecoupling agent is silane.
 45. The product mixture of claim 44 whereinthe plant fibers are less than 250 microns (2.5×10⁻⁴ m) in size.
 46. Theproduct of claim 42 wherein the mineral additives are one or more of theadditives from the group of additives consisting of metallic particles,silicates, silica, silica sand or glass particles.
 47. The method ofclaim 1 wherein the plant fiber mixture comprises one or more additivesfrom the group of additives consisting of a release agent; catalyst;metallic particles; fire retardant; a surface agent; pigment; colouringagent; a mineral additive from the second group of additives consistingof silicates, silica, silica sand, sand, glass fibers, and glass beads;and a coupling agent.
 48. The method of claim 2 wherein the temperatureof the mold is between 100° C. and 220° C.
 49. The method of claim 3wherein the temperature of the mold is between 160° C. and 220° C.
 50. Amethod of manufacturing a high density plant fiber material frompowdered plant fibers which have not been preformed, comprising thesteps of: introducing into a mold a mixture comprising powdered plantfiber particles having a size of less than 500 microns (5×10⁻⁴ m),thermoset binding agent between at least 0.1 per cent and 50 per cent byweight of the plant fiber particles, and the thermoset binding agent isselected from the group of agents consisting of unsaturated polyesterresin, polymeric diphenyl methane di-isocyante, methane di-isocyante,melamine, urea, phenolic formaldehydes and ester containing compounds;operating the mold at a temperature between 40° C. to 300° C.; applyinga pressure of at least 500 psi (3.4 Mpa) to the contents of the mold;compressing the contents of the mold to an average density of at least75 pounds per cubic foot (1200 Kg/m³); and removing the contents fromthe mold.
 51. The method of claim 50 wherein the concentration ofthermoset binding agent is more than 1 per cent and less than 25 percent by weight of plant fibers.
 52. The method of claim 50 wherein theconcentration of thermoset binding agent is less than 10 per cent byweight of plant fibers.
 53. The method of claim 51 wherein the contentsof the mold are compressed to an average density of more than 80 poundsper cubic foot (1280 Kg/m³).
 54. The method of claim 51 wherein thecontents of the mold are compressed to an average density of more than90 pounds per cubic foot (1440 Kg/m³).
 55. The method of claim 51wherein the mixture further comprises one or more mineral additives andnon-mineral additives in a total concentration of between 2 per cent to50 per cent by weight of plane fibers.
 56. The method of claim 51wherein the mixture comprises mineral additives in a concentration of upto 30 per cent by weight of plant fibers.
 57. The method of claim 51wherein the mixture comprises mineral additives in a concentration of upto 10 per cent by weight of plant fibers.
 58. The method of claim 57wherein the mixture further comprises a coupling agent.
 59. The methodof claim 58 wherein the mineral additives are one or more of theadditives selected from the group consisting of silicates, silica,silica sand, and glass particles.
 60. A method of forming a high densityplant fiber product from powdered plant fibers which have not beenperformed, comprising the steps of: a step of mixing one or both of (i)a first amount of powdered plant fiber having a size of less than 500microns (5×10⁻⁴ m) and a thermoset binding agent wherein the thermosetbinding agent is selected from the group of agents consisting ofunsaturated polyester resin, polymeric diphenyl methane di-isocyante,isocyante, methane di-isocyante; melamine, urea, phenolic formaldehydesand ester containing compounds and (ii) a second amount of powderedplant fiber of less than 500 microns (5×10⁻⁴ m) and one or moreadditives; preparing a plant fiber mixture containing thermoset bindingagent, wherein the thermoset binding agent is selected from the group ofagents consisting of unsaturated polyester resin, polymeric diphenylmethane di-isocyante, methane di-isocyante, melamine, urea, phenolicformaldehydes and ester containing compounds, in a concentration ofbetween 0.1 per cent and 50 percent by weight of powdered plant fiber,comprising mixing one or both of the first and second amounts with otheradditives; introducing the plant fiber mixture into the cavity of amold; compressing the mixture by applying a pressure of at least 500 psi(3.4 Mpa) to the surface of the mixture; heating the mold cavity tobetween 40° C. to 300° C.; compressing the contents of the mold to adensity of at least 75 pounds per cubic foot (1200 kg/m³); and removingthe compressed contents from the mold.
 61. The method of claim 60wherein the concentration of binding agent is between 0.1 per cent and25 per cent by weight of powdered plant fiber.
 62. The method of claim60 wherein the concentration of binding agent is between 10 per cent and25 per cent by weight of powdered plant fiber.
 63. The method of claim50 wherein the powdered plant fiber particles have a moisture content ofbetween 5 and 20 per cent by weight of plant fibers.
 64. A method ofmanufacturing a high density plant fiber material from powdered plantfibers which have not been preformed, comprising the steps of:introducing a mold a mixture comprising powdered plant fiber particleshaving a size of less than 500 microns (5×10⁻⁴ m) and a moisture contentof between 5 and 20 percent by weight of plant fibers, thermoset bindingagent between at least 0.1 per cent and 25 per cent by weight of theplant fiber particles, and the thermoset binding agent is selected fromthe group of agents consisting of unsaturated polyester resin, polymericdiphenyl ethane di-isocyante, methane di-isocyante, melamine, urea,phenolic formaldehydes and ester containing compounds; operating themold at a temperature between 40° C. to 300° C.; applying a pressure ofat least 500 psi (3.4 Mpa) to the contents of the mold; compressing thecontents of the mold to an average density of at least 60 pounds percubic foot (960 Kg/m³); and removing the contents from the mold.
 65. Themethod of claim 64 wherein the concentration of thermoset binding agentis less than 10 per cent by weight of plant fibers.
 66. The method ofclaim 65 wherein the mixture further comprises one or more mineraladditives and non-mineral additives in a total concentration of between2 per cent to 10 per cent by weight of plant fibers.
 67. A method ofmanufacturing a high density plant fiber material from powdered plantfibers which have not been preformed, comprising the steps of:introducing into a mold a mixture comprising powdered plant fiberparticles having a size of less than 500 microns (5×10⁻⁴ m), thermosetbinding agent between at least 0.1 per cent and 10 per cent by weight ofthe plant fiber particles, and the thermoset binding agent is selectedfrom the group of agents consisting of unsaturated polyester resin,polymeric diphenyl methane di-isocyante, methane di-isocyante, melamine,urea, phenolic formaldehydes and ester containing compounds; operatingthe mold at a temperature between 40° C. to 300° C.; applying a pressureof at least 2000 psi (13.6 Mpa) to the contents of the mold; compressingthe contents of the mold to an average density of at least 75 pounds percubic foot (1200 Kg/m³); and removing the contents from the mold.
 68. Amethod of manufacturing a high density plant fiber material frompowdered plant fibers which have not been preformed, comprising thesteps of: introducing into a mold a mixture comprising powdered plantfiber particles having a size of less than 250 microns (5×10⁻⁴ m),thermoset binding agent in a concentration of more than 1 per cent andless than 25 per cent by weight of the plant fiber particles, and thethermoset binding agent is selected from the group of agents consistingof unsaturated polyester resin, polymeric diphenyl methane di-isocyante,methane di-isocyante, melamine, urea, phenolic formaldehydes and estercontaining compounds; operating the mold at a temperature between 40° C.to 300° C.; applying a pressure of at least 3000 psi (20.4 Mpa) to thecontents of the mold; compressing the contents of the mold to an averagedensity of at least 75 pounds per cubic foot (1200 Kg/m³); and removingthe contents from the mold.
 69. A method of manufacturing a high densityplant fiber material from powdered plant fibers which have not beenpreformed, comprising the steps of: introducing into a mold a mixturecomprising powdered plant fiber particles having a size of less than 500microns (5×10⁻⁴ m), thermoset binding agent in concentration which ismore than 1 per cent and less than 25 per cent by weight of the plantfiber particles, and the thermoset binding agent is selected from thegroup of agents consisting of unsaturated polyester resin, polymericdiphenyl methane di-isocyante, methane di-isocyante, melamine, urea,phenolic formaldehydes and ester containing compounds; operating themold at a temperature between 40° C. to 300° C.; applying a pressure ofat least 1000 psi (6.8 Mpa) to the contents of the mold; compressing thecontents of the mold to an average density of at least 75 pounds percubic foot (1200 Kg/m³); and removing the contents from the mold. 70.The method of claim 69 wherein the contents of the mold are compressedto an average density of more than 80 pounds per cubic foot (1280Kg/m³).
 71. The method of claim 70 wherein the contents of the mold arecompressed to an average density of more than 90 pounds per cubic foot(1440 Kg/m³).
 72. A plant fiber product compressed to an average densityof at least 75 pounds per cubic foot (1200 Kg/m³) made substantiallyfrom powdered plant fibers containing protolignin, the fibers having asize of less than 500 microns (5×10⁻⁴ m), and a thermoset binding agentin a concentration of between about 0.1 per cent and 50 per cent byweight of plant fiber, wherein the thermoset binding agent is selectedfrom the group of agents having unsaturated polyester resin, polymericdiphenyl methane di-isocyante, methane di-isocyante, melamine, urea,phenolic formaldehydes and ester containing compounds.
 73. The productof claim 72 wherein the average density is at least 80 pounds per cubicfoot (1280 Kg/m³).
 74. The product of claim 73 having an average densityof at least 90 pounds per cubic foot (1440 Kg/m³).
 75. The product ofclaim 73 wherein the size of the plant fibers is less than 250 microns(2.5×10⁻⁴ m).